Sunland Park, N.M.; and Ciudad Juárez, Mexico — For decades, most Mexicans caught trudging across the desolate and dusty hills of Sunland Park, N.M., have been fingerprinted and promptly sent back over the border.

But in an effort to slow the revolving door of job-seeking immigrants willing to test high-tech sensors, bike patrols, and fences that guard the American boundary here, border patrol agents have initiated a tough zero-tolerance policy along this 12-mile zone that stretches west from El Paso, Texas.

Anyone caught crossing illegally, agents say, will be arrested and prosecuted, whether it's their first or 50th try. If they attempt to come back within five years, they face a felony charge.

For critics, the policy, which comes amid a tougher culture of border enforcement, will push immigrants into the hands of smugglers and will add to already crowded US jails and burden its courts. For supporters, however, it's a significant attempt to stop a human tide that, despite ebbs, continues largely unabated.

"Despite all this, they continue to come in," says US border patrol agent Ramiro Cordero, pointing to a mix of barriers and cameras. "This solution is zero tolerance.... It is obviously going to stop them." US border patrol officials says this program aimed at deterrence is already working.

From Feb. 25 – when the program called "No Pass" was launched along just three miles near El Paso – until March 9, 62 immigrants were apprehended, compared with 189 in the same period the year before. That's a 78 percent decrease – and to the US border patrol a sign that their principal goal of prevention is working.

The program also operates under the name "Lockdown," in an area further west along New Mexico's border. Almost all of those caught in this zone have been prosecuted.

Albelardo Flores Rojo is one of the most recent. He was detained just outside El Paso. Had he crossed east of the No Pass zone, the Guadalajara native, who was on his way to meet relatives in Los Angeles, most likely would have been returned to Mexico within hours.

Instead, last week he was at the US border patrol's processing center, wearing a red bracelet to signify he will not be going home.

"I was scared, I had no idea I'd go to jail," says Mr. Flores Rojo.

In the past, immigrants who have attempted to cross repeatedly, and all of those with criminal records, were prosecuted. Now, there is no distinction between first-time crossers and those with criminal pasts. All will face charges.

The program has provoked a hailstorm of criticism.

"This is not going to stop immigration, it's only going to push them into more isolated areas," says Fernando Garcia, executive director of the Border Network for Human Rights in El Paso. "They will need more help from smugglers. It will only increase the number dying across the border."

Many of those crossing in this area are caught wading across the Rio Grande, sneaking across the roads under constant vigil, even driving four-wheel trucks across wire tied to wooden poles. Many also attempt to cross the canals outside El Paso.

Of 29 deaths last year, says Mr. Cordero, a border patrol spokesman, some 13 drowned in waters that can have undercurrents of up to 30 miles per hour.

"People say tougher enforcement makes the process less safe," he says, "but in this case it really is about safety."

At the Casa del Migrante in Ciudad Juárez, Mexico, across the border from El Paso, those waiting to cross into the US say they are unfazed by the policy.

Alfredo Santo, who has a job making bricks until he earns enough money to attempt the journey, says he has no doubts he'll elude officials – so he doesn't have to worry about more punitive policies.

"Even if they have to spend time in jail, it won't stop them," she says. "That is what people in the US do not understand."

The No Pass and Lockdown programs have been piloted in other parts of the border, including Yuma and Tucson, Ariz.

In the busy Tucson sector, local officials have expressed concerns in the local media about overcrowded jails and courts, since the program was implemented in January.

In the El Paso sector, some 75,000 people were apprehended last year and some worry the system will be overwhelmed by the new program.

"What I'm bracing for is an increase in the number of cases brought," says Andre Poissant, an El Paso-based attorney whose clients, two Mexican brothers and cousin, were among the first to be caught and charged under the No Pass plan. They received 12-day sentences.

Cordero says that not all immigrants prosecuted will get jail time, which can range from several days to several months. He says that some will face expedited removal. In both cases, they still face felony charges if they enter again within five years.

Still, some say this is an easy solution to a problem that allows the US and Mexico to avoid the real challenges at hand.

"Mexico needs to get its act together with development programs," says Tony Payan, an assistant professor of political science at the University of Texas at El Paso. "And the US has to find a way to get labor into the US in an organized, legal way."